1. Field of the Invention
This invention relates generally to the field of automatic swimming pool cleaners, and more particularly, to reverse fluid flow valves for use with fluid supply lines connected to pool cleaners.
2. Description of the Related Art
A swimming pool normally includes a water filtration system for removing dirt and debris from the pool water. Such filtration systems typically include a circulation pump which is installed outside the swimming pool and a piping system for coupling the circulation pump to the swimming pool. The circulation pump draws water from the swimming pool for delivery through the piping system to a filter unit.
A conventional water filtration system is not designed to remove silt and debris which tends to settle irrespective of size onto the floor and sidewalls of a swimming pool.
To address the foregoing problems, automatic swimming pool cleaners for cleaning the floor and sidewalls of a swimming pool are well known. There are generally four types of pool cleaners in the pool cleaning market: pressure or return side cleaners; suction cleaners; electric cleaners and in-floor cleaners.
Generally, "pressure" or return-side cleaners perform superior cleaning over the other three types of cleaners. Pressure-type cleaners use pressurized water from a pump into the cleaner to sweep and collect debris into a bag carried by the cleaner.
Pressurized cleaners can be characterized into at least two categories - those requiring a booster pump and those which do not. Booster pumps are used in conjunction with the pools skimmer pump to provide pressurized water to the cleaner at a rate sufficient to operate the cleaner effectively.
One particular type of known automatic pressure cleaner is shown and described in co-pending U.S. patent application Ser. No. 09/108,283, fully incorporated herein by reference. Prior art cleaners were designed to be used with and required a booster pump be installed in order to generate sufficient pressure to the apparatus to power the device about the pool. In older pool installations, the pool's cleaning system may require retrofitting to install the booster pumps in order to properly operate the device. The apparatus described in the application Ser. No. 09/108,283 patent does not require a booster pump; rather, it is designed to operate using the lower fluid pressure of the pool's water existing filtration pump.
This type of cleaner (as well as other types of cleaners) operates on pressurized water that is supplied to the cleaner through a supply hose. The water is used in part to drive the blades of a turbine which, in turn, rotates two or more of the wheels, and in part to induce a flow of pool water upwardly through the cleaner suction mast and into the collection bag.
The drive wheels and a thrust jet propel the cleaner along the floor and sidewalls of the swimming pool. When the pool cleaner reaches an obstruction preventing further direct forward travel, the drive wheels impart a turning movement, causing the cleaner to turn and continue travel in a different direction. Alternatively, when the cleaner travels along the pool floor and reaches a smoothly curved region merging with a sidewall, the cleaner tends to travel through the curved region and crawl at least part way up the pool sidewall until the cleaner falls by gravity back to the floor of the pool. A ballast float mounted at the upper rear of the cleaner helps assure that the cleaner will land upright on the pool floor and resume travel in a forward direction.
In general, back-up valves provide additional insurance that a cleaner will not get stuck in edges or corners of pools by forcing a reversal of direction of the cleaner at regular intervals.
Construction of backup valves is well known. In particular, one such valve includes a housing containing a fly wheel, rotating cover plate, and gearing. The housing has a water inlet, and at least two water outlets directed generally toward the opposite end of the hosing from the inlet. One outlet is coupled by the supply line to the cleaner, while the other allows water to enter the pool directly, in a direction generally parallel to the supply line and the first outlet. Water is also prevented from entering the cleaner, thereby freeing backward movement of the cleaner. Water in the supply line enters the housing and drives the impeller to rotate the rotating cover plate to cover the fist outlet and redirect water in the housing to the second outlet for a period of time determined by the gearing. The rotation of the gearing and the rotating cover plate determines the amount of time that water is allowed to flow to the cleaner, and the amount of time water flows into the pool to "back-up" the cleaner.
With low pressure cleaners, that is, cleaners operating without the benefit of an additional booster pump, a difficulty has been found in obtaining the desired timing in backup valves due to the lower pressure of the water entering the inlet of the valve. Specifically, there is not enough pressure from the main water pressure source--without a booster pump--to accurately and regularly drive the impeller in the valve to ensure a constant spin rate and in some cases, not enough to even turn the wheel.
Generally back-up valves are used with pressure cleaners to ensure that the cleaner will not become otherwise jammed or stuck. The reverse valves contain a timing mechanism, such as a impeller and gears, which operate to direct the flow of water in the supply line out of the valve for some period of time in order to create tension on the line and dislodge any stuck cleaner.